1. Field of the Invention
The present invention relates to a communication apparatus such as a facsimile apparatus or the like that can especially make ECM communications.
2. Related Background Art
A conventional facsimile apparatus based on the ITU-T recommendations encodes an image signal by a predetermined coding scheme, and then adds an RTC signal. 256 bytes of such information form one frame, and 256 frames form one block. Information exceeding 256 frames is divided into a plurality of partial pages upon transmission.
Since the encoded image signal and RTC signal (return to control) are processed as indistinctive information, and are transmitted while being divided in units of frames and blocks (partial pages), the RTC signal is often divided into two blocks (two partial pages).
When the RTC signal extends across two blocks, one physical page is divided into two partial pages. In the first partial page, the RTC signal is transmitted after the image signal, and the protocol signal herein is a PPS-NULL signal. In the next partial page, the RTC signal alone is transmitted, and the protocol signal herein is a PPS-Q (Q: MPS, EOM, or EOP) signal.
Upon reception of the PPS-NULL signal, the receiver should couple the first and second partial pages, and record them as one physical page. However, it was confirmed in communication tests that some facsimile apparatus available from manufacturers other than CANON Inc. record the first partial page as one physical page, and record the second partial page as another physical page (a blank sheet is output as the second page).
The communication tests also revealed the following fact. That is, upon reception of the above-mentioned signal, another facsimile apparatus (not a CANON product) detects the RTC signal by decoding the first partial page, and determines that reception for one physical page is complete. When reception of the next partial page is started, such facsimile apparatus terminates due to errors arising from the absence of effective line information.